Synthetic fibers with enhanced soil resistance and methods for production and use thereof

ABSTRACT

Synthetic fibers with enhanced soil resistance, yarns and carpets prepared from these fibers and compounds and methods for their production are provided.

FIELD OF INVENTION

The present disclosure relates to a soil resistance-affecting additive and synthetic fibers made therefrom having enhanced soil resistance. The present disclosure also relates to articles of manufacture prepared from these fibers and methods for their production and use.

BACKGROUND

In the production of textiles, such as carpet and apparel, it is common to treat substrates with a composition to impart desirable properties, such as resistance to soiling by particulates and dry soil.

Various fluorochemical compositions, and methods for their application, have been described for commercial use to impart soil resistance to carpets.

For example, U.S. Pat. No. 5,882,762 to Goeman discloses carpet yarn comprising a plurality of filaments of thermoplastic polymers with a fluorochemical or non-fluorochemical hydrophilicity imparting compound dispersed within the filaments. It was found that the presence of the hydrophilicity imparting compound in the filaments allowed production of carpet yarn with a reduced amount of spin finish or even without the spin finish normally required. Carpets produced using such yarn were less susceptible to soiling.

U.S. Pat. No. 8,247,519 discloses articles fabricated from polyamides and comprising fluoroether functionalized aromatic moieties with soil and oil resistance.

U.S. Pat. No. 8,304,513 discloses soil resistant polyester polymers, particularly poly(trimethylene terephthalate) comprising fluorovinylether functionalized aromatic repeat units.

U.S. Pat. No. 8,697,831 discloses soil resistant polyamides, particularly nylon 6,6 and nylon 6 comprising fluoroether functionalized aromatic repeat units.

Therefore, there is a need to provide polymeric fibers that have improved built-in soil resistance.

SUMMARY OF THE INVENTION

An aspect of the present invention relates to a synthetic fiber comprising a first fiber forming polymer, and a soil resistance-affecting additive.

In one nonlimiting embodiment, the soil resistance-affecting additive is present in the fiber at a range from about 0.1 to 10 percent by weight.

In one nonlimiting embodiment, at least a portion of the soil resistance-affecting additive is present on the surface of the fiber. Preferred is that this portion present on the surface is sufficient to impart soil resistant properties to the fiber.

In one nonlimiting embodiment, at least a portion of the soil resistance-affecting additive is not polymerized with first fiber forming polymer.

In one nonlimiting embodiment, at least a portion of the soil resistance-affecting additive has bloomed to the surface of the fiber.

In one nonlimiting embodiment, the first fiber forming polymer of the synthetic fiber is a polyamide, a polyester, or a polyolefin, or any combination thereof

In one nonlimiting embodiment, the soil resistance-affecting additive of the synthetic fiber is an aromatic sulfonate or an alkali metal salt thereof. In another nonlimiting embodiment, the soil resistance-affecting additive is a polymer.

Another aspect of the present invention relates to a synthetic fiber comprising a first fiber forming polymer, a second polymer and a soil resistance-affecting additive. In one nonlimiting embodiment, the first fiber forming polymer is present in a range from about 80 to 99 percent by weight; the second polymer is present in a range from about 0.2 to 10 percent by weight; and the soil resistance-affecting additive is present in the fiber at a range from about 0.1 to 10 percent by weight.

In one nonlimiting embodiment, the second polymer of the synthetic fiber has a melting point which is less than the melting point of the first fiber forming polymer and/or does not cause the synthetic fiber to fibrillate.

In one nonlimiting embodiment, the second polymer is a polyolefin, a polylactic acid or a polystyrene or any combination thereof.

In one nonlimiting embodiment, the soil resistance-affecting additive of the synthetic fiber is an aromatic sulfonate or an alkali metal salt thereof.

Another aspect of the present invention relates to articles of manufacture, at least a portion of which comprises one or more of these synthetic fibers. Nonlimiting examples of these articles of manufacture include yarns and fabrics formed from the synthetic fibers and carpets formed from the yarns.

Yet another aspect of the present invention relates to method for producing a synthetic fiber with enhanced soil resistance.

In one nonlimiting embodiment, the method comprises forming a polymer melt of a first fiber forming polymer and a soil resistance-affecting additive. In this nonlimiting embodiment, the soil resistance-affecting additive is present in a range from about 0.1 to 10 percent by weight. A synthetic fiber is then formed from the polymer melt.

In another nonlimiting embodiment, the method comprises forming a polymer melt comprising a first fiber forming polymer and a masterbatch compound. In this nonlimiting embodiment, the masterbatch compound comprises a second polymer and a soil resistance-affecting additive. In this nonlimiting embodiment, the first fiber forming polymer is present in a range from about 80 to 99 percent by weight, and the masterbatch compound is present in a range from about 0.2 to 20 percent by weight. A synthetic fiber is then formed from the polymer melt.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plot which shows soiling performance after the carpet samples were hot water extracted before they were soiled. This plot indicates the durability of the soiling performance of the carpet samples. As indicated in FIG. 1, the examples with the inventive embodiments performed the best after HWE treatment.

FIG. 2 is a plot of colorimetric L* progression upon the soiling and vacuum cleaning (S&V), and hot water extraction (HWE) cycles of a single set of carpets. H denotes that this carpet was pre-HWE 3× before the testing to mimic scouring.

FIG. 3 is a SEM micrograph of a trilobal filament from an embodiment of the current invention. Depicted is pigmented 1.0 wt % dimethyl-5-sulfoisophthalate, sodium salt (NaSIM) in a polyester fiber where the masterbatch carrier of the NaSIM is polypropylene.

FIG. 4 is a set of SEM micrographs and XDS spectra of longitudinal sections of an embodiment of the current invention. Depicted is a trilobal filament of NaSIM in pigmented PET where the masterbatch carrier of the NaSIM is polypropylene.

FIG. 5 is a SEM micrograph of an example of an embodiment of the current invention. Depicted is a trilobal filament of pigmented 0.5 wt % 5-sulfoisophthalic acid, sodium salt (SSIPA) in a polyester fiber that was added with a polypropylene masterbatch carrier.

DETAILED DESCRIPTION OF THE INVENTION

Provided by this disclosure are fibers with enhanced soil resistance, yarns, fabrics and carpets prepared from these fibers, and methods and masterbatch compositions for their production.

In one nonlimiting embodiment, the synthetic fiber comprises a first fiber forming polymer and a soil resistance-affecting additive.

Examples of first fiber forming polymers which can be used in this embodiment include, but are not limited to, polyamides, polyesters, and polyolefins and any blends or combinations thereof.

Suitable polyamides include fiber forming polyamides known in the art to be suitable for the formation of bulked continuous filament fibers, having sufficient viscosity, tenacity, chemical stability and crystallinity to be at least moderately durable in such application. The polyamide may be selected from the group consisting of nylon 5,6; nylon 6,6; nylon 6; nylon 7; nylon 11; nylon 12; nylon 6/10; nylon 6/12; nylon DT; nylon 6T; nylon 6I; and blends or copolymers thereof. In one embodiment the polyamide is nylon 6,6 polymer.

Suitable polyolefins include polypropylene.

Suitable polyesters include fiber forming polyesters known in the art. The polyester resin may be selected from the group consisting of polyethylene terephthalate (PET), polybutylene terephthalate, polytrimethylene terephthalate, polyethylene naphthalate, polylactic acid (PLA) and blends or copolymers thereof.

In this embodiment, the first fiber forming polymer is present in the synthetic fiber in a range from about 90 to 99 percent by weight.

It had previously been known to enhance stain resistance of polyamide fibers by forming the fibers from polyamides prepared by copolymerizing monomers, some of which contain sulfonate moieties. U.S. Pat. No. 6,133,382, U.S. Pat. No. 6,334,877 and U.S. Pat. No. 6,589,466 disclose a fiber-forming polyamide and a method to improve stain resistance of polyamide fibers by melt compounding a sulfonated polyester concentrate with fiber-forming polyamide compositions subsequent to polymerization of the polyamide and the concentrate and prior to the formation of the fibers. U.S. Pat. No. 6,433,107 and U.S. Pat. No. 6,680,018 disclose a similar composition and method wherein the stain resistance of polyamide fibers is improved by melt compounding a combination of sulfonated polyester concentrate and thermoplastic carrier resin with fiber-forming polyamide compositions subsequent to polymerization of the polyamide and prior to the formation of the fibers.

In addition, none of the disclosures referred to above contemplate the improvement of soil resistance for polyester-based fiber compositions, where the preponderance of the fiber composition is polyester. Furthermore, polyester compositions having up to 2% content by mass of sulfonic acid moieties are not deemed to be effectively soil resistant. As a result, there has been a long felt need to provide polymeric materials, especially polyester based materials, with improved soil resistance.

Through undue experimentation, the inventors surprisingly found that soil resistance of synthetic fibers could be improved by the addition of the soil resistance-affecting additive disclosed herein.

The synthetic fiber of this embodiment further comprises a soil resistance-affecting additive. In one nonlimiting embodiment, the soil resistance-affecting additive is an aromatic sulfonate or an alkali metal salt thereof. Nonlimiting examples include 5-sulfoisophthalic acid, sodium salt (SSIPA) and dimethyl-5-sulfoisophthalate, sodium salt (NaSIM). In another nonlimiting embodiment, the soil resistance-affecting additive is a polymer. A nonlimiting example of a polymer useful as a soil resistance-affecting additive in this embodiment is polypropylene.

In this embodiment, the soil resistant additive is present in the synthetic fiber in a range from about 0.1 to about 10 percent by weight.

In another nonlimiting embodiment, the synthetic fiber of the present disclosure comprises a first fiber forming polymer, a second polymer and a soil resistance-affecting additive.

Examples of first fiber forming polymers which can be used in this embodiment include, but are not limited to, polyamides, polyesters, and polyolefins and any blends or combinations thereof.

Suitable polyamides include fiber forming polyamides known in the art to be suitable for the formation of bulked continuous filament fibers, having sufficient viscosity, tenacity, chemical stability and crystallinity to be at least moderately durable in such application. The polyamide may be selected from the group consisting of nylon 5,6; nylon 6,6; nylon 6; nylon 7; nylon 11; nylon 12; nylon 6/10;, nylon 6/12; nylon DT; nylon 6T; nylon 6I; and blends or copolymers thereof. In one embodiment the polyamide is nylon 6,6 polymer.

Suitable polyolefins include polypropylene.

Suitable polyesters include fiber forming polyesters known in the art. The polyester resin may be selected from the group consisting of polyethylene terephthalate, polybutylene terephthalate, polytrimethylene terephthalate, polyethylene naphthalate, polylactic acid (PLA) and blends or copolymers thereof.

In this embodiment, the first fiber forming polymer is present in the synthetic fiber in a range from about 80 to 99 percent by weight.

The synthetic fiber of this embodiment further comprises a soil resistance-affecting additive. In one nonlimiting embodiment, the soil resistance-affecting additive is an aromatic sulfonate or an alkali metal salt thereof. Nonlimiting examples include 5-sulfoisophthalic acid, sodium salt and dimethyl-5-sulfoisophthalate, sodium salt.

In this embodiment, the soil resistant additive is present in the synthetic fiber in a range from about 0.1 to about 10 percent by weight.

The synthetic fiber of this embodiment further comprises a second polymer. Preferred is that the second polymer having a melting point that is less than the melting point of the first fiber forming polymer. Also preferred is that the presence of the second polymer does not cause the synthetic fiber to fibrillate. Examples of second polymers useful in the present disclosure include, but are not limited to, polyolefins, polylactic acid and polystyrene, or any blend or combination thereof. In one nonlimiting embodiment, the polyolefin is an unmodified polyolefin. In another nonlimiting embodiment, the second polymer is polypropylene.

In one nonlimiting embodiment, the second polymer is present in the synthetic fiber in a range from about 0.5 to about 10 percent by weight.

In the synthetic fibers of the present invention, at least a portion of the soil resistance-affecting additive is present on the surface of the fiber. Preferred is that this portion present on the surface of the fiber is sufficient to impart soil resistant properties to the fiber.

Further, in the synthetic fibers of this disclosure at least a portion of the soil resistance-affecting additive is not polymerized with the first fiber forming polymer. Instead, preferred in the synthetic fibers of this disclosure is that at least a portion of the soil resistance-affecting additive has bloomed to the surface of the fiber.

In one nonlimiting embodiment, the synthetic fiber of this disclosure has a multilobal cross section. In another nonlimiting embodiment, a majority (meaning greater than 50%), at least 75% or substantially all of the soil resistant additive present on the surface of the fibers is located in the area between the lobes.

The present disclosure also relates to articles of manufacture comprising at least a portion of a synthetic fiber or fibers of this disclosure. Examples of such articles include, but are not limited to, yarns prepared from the synthetic fibers, as well as fabrics and carpets prepared from the synthetic fibers and/or yarns.

Also provided by this disclosure are processes for forming these synthetic fibers with enhanced soil resistance.

In one nonlimiting embodiment, the process comprises forming a polymer melt comprising a first fiber forming polymer and a soil resistance-affecting additive. In this nonlimiting embodiment, the soil resistance-affecting additive is present in a range from about 0.1 to 10 percent by weight. A synthetic fiber is then formed from the polymer melt. In this embodiment, the soil resistance-affecting additive used in the process can be an aromatic sultanate or an alkali metal salt thereof, or a polymer. Nonlimiting examples include 5-sulfoisophthalic acid, sodium salt; dimethyl-5-sulfoisophthalate, sodium salt; and polypropylene.

In one nonlimiting embodiment, the soil resistance-affecting additive is added to the polymer melt by powder addition. In another nonlimiting embodiment, the soil resistance-affecting additive is added as a powder capsule.

In another nonlimiting embodiment, the process comprises forming a polymer melt comprising a first fiber forming polymer and a masterbatch compound. In this nonlimiting embodiment, the masterbatch compound comprises a second polymer and a soil resistance-affecting additive. The first fiber forming polymer is present in a range from about 80 to 99 percent by weight, and the masterbatch compound is present in a range from about 1 to 20 percent by weight. In one nonlimiting embodiment, no additional steps are required to remove volatiles while forming the polymer melt. A synthetic fiber is then formed from this polymer melt. In this embodiment, the soil resistant additive used in the process can be an aromatic sulfonate or an alkali metal salt thereof. Nonlimiting examples include 5-sulfoisophthalic acid, sodium salt and dimethyl-5-sulfoisophthalate, sodium salt.

Also provided by the present disclosure is a masterbatch compound. The masterbatch compound comprises a thermoplastic carrier, also referred to herein as second polymer. Examples of thermoplastic carriers useful in the masterbatch include, but are not limited to polyolefins, polylactic acid, polystyrene, or a blend or copolymer thereof. In one nonlimiting embodiment, the thermoplastic carrier is a polyolefin. In one nonlimiting embodiment the thermoplastic carrier is an unmodified polyolefin. In another nonlimiting embodiment, the thermoplastic carrier is polypropylene.

In one nonlimiting embodiment, the thermoplastic carrier is present in the masterbatch compound in a range from about 40 to about 90 percent by weight. In one nonlimiting embodiment, the masterbatch compound comprises about 50% of the thermoplastic carrier.

The masterbatch compound further comprises a soil resistance-affecting additive. Suitable soil resistance-affecting additives include, but are not limited to aromatic sulfonates and alkali metal salts thereof, such as 5-sulfoisophthalic acid, sodium salt and dimethyl-5-sulfoisophthalate, sodium salt. In one nonlimiting embodiment, the soil resistance-affecting additive is present in the masterbatch compound in a range from about 10 to about 60 percent by weight.

In one nonlimiting embodiment, the masterbatch compound has a moisture content less than about 200 ppm, more preferably less than about 50 ppm. In another nonlimiting embodiment, the masterbatch compound is not dried or conditioned prior to forming the polymer melt.

The masterbatch compound may further comprise other additives, to be used to confer additional benefits to articles upon polymer melt extrusion and melt spinning. Examples of such additives are inorganic pigments, and ultraviolet (UV) light absorbers or optical brightening agents. Examples of inorganic pigments are titanium dioxide, barium sulfate, carbon black, manganese dioxide, and zinc oxide. Examples of UV light absorbers or optical brightening agents are 2,2′-(1,2-ethenediyldi-4,1 phenylene)bisbenzoxazole, available commercially by Eastman Chemical Company under the tradename Eastobrite® OB-1, and 2,2′-(2,5-thiophenediyl)bis(5-tert-butylbenzoxazole, available commercially by Mayzo, Inc. under the tradename Benetex® OB.

In one nonlimiting embodiment, the masterbatch compound is present in fiber in a range from about 1 to about 20 percent by weight.

The present disclosure also relates to articles of manufacture, at least a portion of which comprises a synthetic fiber produced in accordance with this process. Nonlimiting examples include yarns prepared from synthetic fibers produced by this process, as well as fabrics and carpets prepared from these synthetic fibers and/or yarns.

In nonlimiting embodiments, masterbatches were prepared with the following soil resistance-affecting additives:

The masterbatches were added at the extruder hopper to a standard bottle-grade PET resin, at 0.5 wt % and 2 wt % actives. The resultant pigmented trilobal PET fibers were processed and tufted into a 30 oz./sq. yd residential cut pile carpet. It was found that the characteristic stain resistance of PET was not negatively impacted by blending with the soil resistant additive. Further, Vetteiinan drum performance was similar to the equivalent control. In Accelerated Drum Soil tests (ASTM D6540-12), however, carpet prepared from fibers of this disclosure containing 4wt % of the masterbatch showed an advantage of 4-5.5 ΔE units as compared to untreated PET, were equivalent to PET carpet treated with anti-soil chemistry comprising synthetic clay nanoparticles (Laponite S482) at 2% owf, and performed better than PET carpet treated with anti-soil chemistry comprising synthetic clay nanoparticles (Laponite® 5482) and fluorochemical (Capstone® RCP) at 1.2% owf. In general a filament in accordance with the present disclosure has an exterior modification ratio (R2/R1) that can be about 1.50 to 3.00, and more particularly can be about 2.15 to 2.85. The modification ratio (MR) for the control items was nominally the same, at 2.5. Modification ratio determinations, in particular for trilobal bulked continuous filaments, are described as disclosed in European Patent 1,518,948, and U.S. Patent Publication 2015 0275400.

Further testing was performed to confirm that the soil resistant additive of this disclosure does not migrate out of the synthetic fibers on its own, during dyeing processes, or with wet cleaning. Clean carpets were aggressively hot water extracted, and then soiled, to monitor any changes in performance. The sustained anti soiling performance data indicated that the additive was not leached from the polymer fibers.

Thus, the synthetic fibers of this disclosure were found to have markedly improved soiling performance in carpet form. Carpets produced from these synthetic fibers have a “built-in,” or fiber bound, anti-soil performance that exceeds current fluorochemical-based topical anti-soil treatment in efficacy. Further, this built-in resistance is more durable than topical treatments for anti-soil which are known to “walk off” with wear and foot traffic so that the topical chemistry is no longer effective. In addition, using the synthetic fibers of this disclosure eliminates the need for topical application of chemicals by downstream carpet mills. Use of a non-fluorinated compound to enhance soil resistance also diminishes possible environmental concerns.

The following sections provide further illustration of the synthetic fiber and fabrics knitted of this invention as well as comparative fibers and fabrics knitted therefrom. These working examples are illustrative only and are not intended to limit the scope of the invention in any way.

Test Method

Accelerated drum soiling is recorded as Delta E, and measured according to ASTM D6540. Within the reproducibility limitations of this test, the relative soiling performance of variously-treated samples may be determined. The test simulates the soiling of carpet in residential or commercial environments to a traffic count level of about 100,000 to 300,000. According to ASTM D6540, soiling tests can be conducted on up to six carpet samples simultaneously using a drum. The base color of the sample (using the L, a, b color space) is measured using the hand held color measurement instrument sold by Minolta Corporation as “Chromameter” model CR-310 (at Camden). This measurement output is in the form L*, a* and b* values and describes a color value in color space. This is the original color value. The carpet sample is mounted on a thin plastic sheet and placed in the drum. Two hundred fifty grams (250 g) of dirty Zytel 101 nylon beads (by DuPont Canada, Mississauga, Ontario) are placed on the sample. The dirty beads are prepared by mixing ten grams (10 g) of AATCC TM-122 synthetic carpet soil (by Manufacturer Textile Innovators Corp., Windsor, N.C.) with one thousand grams (1000 g) of new Nylon Zytel 101 beads. One thousand grams (1000 g) of %-inch diameter steel ball bearings are added into the drum. The drum is run for 30 minutes with direction reversal and the sample removed. After removal the carpet is cleaned with a vacuum cleaner and the chromameter is used again to measure the color of the carpet after cleaning. The difference between the color measurements of each carpet (before and after soiling and cleaning) is the total color difference, ΔE*, and is based on L*, a*, and b* color differences in color space, known to those skilled in the field where

ΔE=√{square root over (((ΔL*)²*(Δa*)²*(Δb*)²))}

AATCC Synthetic Carpet Soil (per MSDS from Year 2000) Component % Weight Peat Moss 38 Cement 17 Hydrated Aluminum Silicate-Kaolin 17 Silica Gel 17 Carbon Lampblack-furnace black 1.75 Mineral Oil 8.75 Ferric Oxide-Red Iron Oxide 0.5 Total 100

AATCC TM175—Stain Resistance: Pile Floor Coverings, and ASTM D5417—Vetterman Drum EXAMPLES

Comparative Examples 1, 2, and 5 and Examples 3, 4, 6, and 7 were produced using pilot scale machinery. The pilot equipment included a 12″ twin screw extruder having five heating zones, a filter screen pack, any of a selection of desired spinnerets, a fiber quenching zone, godet rolls, and winders. A standard spinning method was used to produce fiber from the pilot scale machinery, as follows: the polymer was extruded through the spinnerets and divided into two 184 filament segments. The molten fibers were then rapidly quenched in a chimney, where cooling air at about 10-15 ° C. was blown past the filaments at four hundred and fifty cubic feet per minute [300-600 cfm] through the quench zone. The filaments were then coated with a lubricant for drawing and crimping. The coated yarns were drawn at about 2422 yards per minute (2.9×draw ratio) using a pair of heated draw rolls. The draw roll temperature was 160° C. The filaments were then forwarded into a dual-impingement hot air bulking jet, similar to that described in Coon, U.S. Pat. No. 3,525,134, teachings of which are herein incorporated by reference, to form two BCF yarns (1000 denier, 5.4 dpf). The temperature of the air in the bulking jet was 180° C.

The spun, drawn, and crimped BCF yarns were tufted into carpets and heat-set on a Superba heat-setting machine at setting temperature of 290° C. The holdup time in the setting zone was about 60 seconds. The heatset carpets were tested according to standard test methods ASTM D6540—Accelerated Soiling of Pile Yarn Floor Covering, AATCC TM193—Aqueous Liquid Repellency, AATCC TM175—Stain Resistance: Pile Floor Coverings, and ASTM D5417—Vetterman Drum.

Comparative Example 1 PET BCF, No Melt Additive, No Topical Anti-Soil Treatment

PET bulked continuous filament (BCF, 1000 denier, 184 filaments) was made on pilot scale machinery. Pigments of various colors were mixed with a PET polymer product made by Indorama, Spartanburg, S.C., USA. The pigments and PET were mixed at the screw feeder. Fibers were spun with no process breaks. This BCF yarn had a wool beige color. It was tufted into carpet having ½″ pile height, 16 stitches per inch, 30 oz per square yard cut pile carpet on a 1/8 gauge tufting machine. The carpet was tested for accelerated soiling, stain repellency, and wear resistance as shown in Table 1 and the FIGS. 1-2.

Comparative Example 2

PET BCF, No Melt Additive, Treated with Topical Soil Resist

PET bulked continuous filament (BCF, 1000 denier, 184 filaments) was made on pilot scale machinery. Pigments of various colors were mixed with a PET polymer product made by Indorama, Spartanburg, S.C., USA. The pigments and PET were mixed at the screw feeder. Fibers were spun with no process breaks. This BCF yarn had a wool beige color. It was tufted into carpet having ¼″ pile height, 16 stitches per inch, 30 oz per square yard cut pile carpet on a 1/8 gauge tufting machine and an anti-soil treatment was applied by spraying the tufted carpet with an anti-soil chemistry comprising clay nanoparticles (Laponite S482, BYK-Chemie GmbH, Wesel, Germany) and fluorochemical (Capstone® RCP, Chemours Co., Wilmington, Del. USA) at 1.2% owf. The carpet was tested for accelerated soiling, stain repellency, and wear resistance as shown in Table 1 and FIGS. 1-2.

Example 3 PET BCF, Masterbatch Additive, 1.0 wt % Masterbatch

PET bulked continuous filament (BCF, 1000 denier, 184 filaments) was made on pilot scale machinery. A masterbatch of polypropylene and sodiosulfonated isophthalic acid, dimethyl ester (1:1 weight ratio) was added in the melt at 1 wt % to a PET polymer product made by Indorama, Spartanburg, S.C., USA. The masterbatch and PET were mixed at the screw feeder. Fibers were spun with no process breaks. This BCF yarn had a wool beige color. It was tufted into carpet having ½″ pile height, 16 stitches per inch, 30 oz per square yard cut pile carpet on a ⅛ gauge tufting machine. The carpet was tested for accelerated soiling, stain repellency, and wear resistance as shown in Table 1 and FIGS. 1-2.

Example 4 PET BCF, Masterbatch Additive, 4 wt % Masterbatch

PET bulked continuous filament (BCF, 1000 denier, 184 filaments) was made on pilot scale machinery. A masterbatch of polypropylene and sodiosulfonated isophthalic acid, dimethyl ester (1:1 weight ratio) was added in the melt at 4 wt % to a PET polymer product made by Indorama, Spartanburg, S.C., USA. The masterbatch and PET were mixed at the screw feeder. Fibers were spun with no process breaks. This BCF yarn had a wool beige color. It was tufted into carpet having ½″ pile height, 16 stitches per inch, 30 oz per square yard cut pile carpet on a ⅛ gauge tufting machine. The carpet was tested for accelerated soiling, stain repellency, and wear resistance as shown in Table 1 and FIGS. 1-2.

Comparative Example 5

PET BCF, No Melt Additive, Treated with Topical Soil Resist, 50 oz/yd² Carpet

PET bulked continuous filament (BCF, 1000 denier, 184 filaments) was made on pilot scale machinery. Pigments of various colors were mixed with a PET polymer product made by Indorama, Spartanburg, S.C., USA. The pigments and PET were mixed at the screw feeder. Fibers were spun with no process breaks. This BCF yarn had a wool beige color. It was tufted into carpet having pile height, 50 oz per square yard cut pile carpet on a ⅛ gauge tufting machine and an anti-soil treatment was applied by spraying the tufted carpet with an anti-soil chemistry comprising clay nanoparticles (Laponite®) and fluorochemicals (Capstone® RCP) at 1.2% owf. The carpet was tested for accelerated soiling, stain repellency, and wear resistance as shown in Table 1 and FIGS. 1-2.

Example 6 PET BCF, Masterbatch Additive, 1.0 wt % Masterbatch

PET bulked continuous filament (BCF, 1000 denier, 184 filaments) was made on pilot scale machinery. A masterbatch of polypropylene and sodiosulfonated isophthalic acid, dimethyl ester (1:1 weight ratio) was added in the melt at 1 wt % to a PET polymer product made by Indorama, Spartanburg, S.C., USA. The masterbatch and PET were mixed at the screw feeder. Fibers were spun with no process breaks. This BCF yarn had a wool beige color. It was tufted into carpet having ½″ pile height, 50 oz per square yard cut pile carpet on a ⅛ gauge tufting machine. The carpet was tested for accelerated soiling , stain repellency, and wear resistance as shown in Table 1 and FIGS. 1-2.

Example 7 PET BCF, Masterbatch Additive, 4 wt % Masterbatch

PET bulked continuous filament (BCF, 1000 denier, 184 filaments) was made on pilot scale machinery. A masterbatch of polypropylene and sodiosulfonated isophthalic acid, dimethyl ester (1:1 weight ratio) was added in the melt at 4 wt % to a PET polymer product made by Indorama, Spartanburg, S.C., USA. The masterbatch and PET were mixed at the screw feeder. Fibers were spun with no process breaks. This BCF yarn had a wool beige color. It was tufted into carpet having ½″ pile height, 50 oz per square yard cut pile carpet on a ⅛ gauge tufting machine. The carpet was tested for accelerated soiling, stain repellency, and wear resistance as shown in Table 1 and FIGS. 1-2.

TABLE 1 Data summary for Examples 1-7. Values shown are averages on multiple (3-5) measurements. Accelerated soiling Stain resistance Vetterman drum ΔE rating rating (ASTM D6540) (AATCC TM175) (ASTM D5417) Example 1 22.0 10 2.5 (5K) Example 2 17.7 10 2.5 (5K) Example 3 20.1 10 2.5 (5K) Example 4 17.8 10 2.0 (5K) Example 5 — 9 2.5 (5K) Example 6 — 9 2.2 (5K) Example 7 — 10 2.2 (5K)

TABLE 2 Mechanical properties measured by ASTM D2256 - Yarns - Tensile by Single Strand method (10 in). Values shown are the averages of 5 measurements Example 1 Example 4 Tensile strain 28.86 27.38 (Extension) at Maximum Load [%] Tenacity at 3.14 2.67 Maximum Load [gf/den] Energy at Maximum 9.52 8.47 Load [in-lbf] Modulus 17.46 14.73 (Automatic) [gf/den] Tensile Strain at 30.32 30.47 Break [%] Maximum Load [lbf] 6.92 5.88 Break Load [lbf] 6.03 4.75 Linear density 1,000 1,000 DENIER [den] Tenacity at Yield 3.06 2.66 (Offset 2%) [gf/den] Energy at Break [J] 1.18 1.15 

1. A synthetic fiber comprising: a) a first fiber forming polymer; and b) a soil resistance-affecting additive present in the fiber at a range from about 0.1 to 10 percent by weight.
 2. The synthetic fiber of claim 1 wherein at least a portion of the soil resistance-affecting additive is present on the surface of the fiber.
 3. (canceled)
 4. (canceled)
 5. The synthetic fiber of claim 1 wherein at least a portion of the soil resistance-affecting additive has bloomed to the surface of the fiber.
 6. (canceled)
 7. The synthetic fiber of claim 1, wherein the fiber has a multilobal cross section and at least 75 percent by weight of the soil resistance-affecting additive present on the surface of the fiber is located in the area between the lobes.
 8. (canceled)
 9. The synthetic fiber of claim 1 wherein the first fiber forming polymer is selected from the group consisting of a polyamide, a polyester, and a polyolefin, and combinations thereof.
 10. (canceled)
 11. The synthetic fiber of claim 5 wherein the polyester is selected from the group consisting of polyethylene terephthalate, polypropylene terephthalate and polybutylene terephthalate, and combinations thereof.
 12. The synthetic fiber of claim 1 wherein the soil resistance-affecting additive is an aromatic sulfonate or an alkali metal salt thereof.
 13. (canceled)
 14. (canceled)
 15. A yarn formed from the synthetic fiber of claim
 1. 16. A carpet formed from the yarn of claim
 15. 17. A fabric formed from the synthetic fiber of claim
 1. 18. A synthetic fiber of claim 1 further comprising: (a) a first fiber forming polymer present in a range from about 80 to 99 percent by weight; (b) a second polymer present in a range from about 0.2 to 10 percent by weight; and (c) a soil resistance-affecting additive present in the fiber at a range from about 0.1 to 10 percent by weight.
 19. (canceled)
 20. (canceled)
 21. (cancelled)
 22. (cancelled)
 23. (cancelled)
 24. (cancelled)
 25. The synthetic fiber of claim 11 wherein the second polymer has a melting point which is less than the melting point of the first fiber forming polymer.
 26. The synthetic fiber of claim 11 wherein the presence of the second polymer does not cause the synthetic fiber to fibrillate.
 27. (canceled)
 28. (canceled)
 29. The synthetic fiber of claim 18 wherein the second polymer is selected from the group consisting of a polyolefin, a polylactic acid and a polystyrene, and combinations thereof.
 30. The synthetic fiber of claim 18 wherein the second polymer is an unmodified polyolefin.
 31. The synthetic fiber of claim 18 wherein the second polymer is polypropylene.
 32. (canceled)
 33. (canceled)
 34. (canceled)
 35. A yarn formed from the synthetic fiber of claim
 11. 36. A carpet formed from the yarn of claim
 17. 37. A fabric formed from the synthetic fiber of claim
 11. 38. A process for forming a synthetic fiber, said process comprising the steps of: a) forming a polymer melt comprising a first fiber forming polymer and a masterbatch compound, wherein the masterbatch compound comprises a second polymer and a soil resistance-affecting additive, and wherein the first fiber forming polymer is present in a range from about 80 to 99 percent by weight, and the masterbatch compound is present in a range from about 0.2 to 20 percent by weight; and b) forming a synthetic fiber from the polymer melt.
 39. (canceled)
 40. (canceled)
 41. (canceled)
 42. (canceled)
 43. (canceled)
 44. (canceled)
 45. (canceled)
 46. (canceled)
 47. The process of claim 20 wherein the second polymer is present in the masterbatch compound in a range from about 20 to 80 percent by weight.
 48. The process of claim 20 wherein the second polymer is selected from the group consisting of a polyolefin, a polylactic acid and a polystyrene, and combinations thereof.
 49. The process of claim 20 wherein the second polymer is an unmodified polyolefin.
 50. The process of claim 20 wherein the second polymer is polypropylene.
 51. The process of claim 20 wherein the first fiber forming polymer is selected from the group consisting of a polyamide, a polyester, and a polyolefin, and combinations thereof.
 52. (canceled)
 53. The process of claim 20 wherein the soil resistance-affecting additive is present in the masterbatch compound in a range from about 20 to 80 percent by weight.
 54. (canceled)
 55. (canceled)
 56. (canceled)
 57. A synthetic fiber formed from the process of claim
 38. 58. A fabric formed from the synthetic fiber of claim
 27. 59. A yarn formed from the synthetic fiber of claim
 27. 60. A carpet formed from the yarn of claim
 29. 